In the construction trade and related industries, it is often necessary to position studs, walls, fasteners, and a variety of other building materials at regularly spaced-apart intervals along a straight line. Typically, such operations are carried out in two steps. First, a conventional chalk string is employed to provide a straight line along the surface of the workpiece. Such chalk strings generally comprise a length of chalk-receptive string contained on a spool within a casing and extensible through an aperture in the casing. As the string is withdrawn through the aperture, it is drawn across a body of marking chalk, the chalk particles adhering to the porous body of the string. The chalked string is stretched against the work surface along the desired line and is snapped against the surface, thereby transferring a portion of the chalk from the string to the surface of the workpiece to provide a straight chalk line. Subsequently, the worker employs a conventional measuring device, such as a folding wooden ruler or a flexible extensible metal measuring tape, and places marks along the chalk line at the desired intervals.
In order to simplify this two-step operation, efforts have been made to provide a chalk line marker which places marks on the workpiece at regularly spaced intervals along the desired line. One such example is found in British Pat. No. 1,026,051 and discloses a chalk line having sleeves of non-chalk-holding material carried by the line at regular intervals. The sleeves of non-chalk-holding material may be of gloss paint applied to the string and may be located at regularly-spaced intervals. According to this device, when the chalk line is laid, the line will have regularly-spaced interruptions along its length as an aid in measuring.
U.S. Pat. No. 4,152,836 discloses another measurement line marker for the placement of regularly-spaced marks in a straight line so as to provide position marks such as for the location of studs. The line marker consists of a thin, flexible metal wire core having a smooth, flexible, non-chalk-holding sleeve covering the major portion of the length of the wire. A number of narrow chalk-holding sleeve segments are strung on the wire at regularly-spaced intervals and are separated by the smooth, non-chalk-holding sleeve sections. When the chalk line is laid, chalk marks corresponding to the desired spacing of the wall studs are laid in a straight line on the work surface. This chalk line marker thus differs from the marker of the aforementioned British patent in that a chalk mark, rather than the absence of a chalk mark, indicates the desired intervals along the line.
These prior art efforts suffer a number of disadvantages. First, these markers are essentially linear in character and depend upon the transition between chalked and unchalked portions of the line to designate the desired intervals. However, in the event that the chalk-holding sections of the markers are not uniformly chalked, or if the marker is not properly snapped against the workpiece, an unintentional interruption or weak intensity chalk line may be mistaken for an interruption designating the regularly spaced interval.
Accordingly, there is a need to provide a line marker for the placement of regularly spaced marks in a straight line wherein the regularly spaced intervals are clearly delineated.
There is a further need to provide an apparatus for placing chalk marks at regularly spaced intervals wherein unintentional interruptions in the chalk line due to inconsistent chalking are not mistaken as designating a desired interval.
Another disadvantage associated with the prior art measurement line markers is their limitation of applying chalk marks only at a single regularly spaced interval. For example, depending upon the application, carpenters may wish to place studs at either sixteen or twenty-four inch intervals. According to the prior art, a line marker may provide marks at sixteen inch intervals; but if an application calls for twenty-four inch intervals, a different line marking device is required.
Accordingly, there is a need to provide a line marker which is capable of placing chalk marks at regularly spaced intervals of either sixteen or twenty-four inches.